html, body {
  height: 100%;
  background-color: #48a0f8;
  overflow: hidden;
}

.box {
  width: 400px;
  height: 310px;
  background-color: #f9db66;
  box-shadow: 5px 5px 5px 5px;
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

.title {
  height: 60px;
  text-align: center;
  line-height: 60px;
  font-size: 26px;
}

form {
  margin: 0 25px;
}

.box a {
  float: right;
}

/* 默认先让注册的盒子隐藏 */
.register {
  display: none;
}